Large commercial passenger carrying airplanes predominantly employ one of two systems for keeping perishable food stuffs and non-perishable drinks at desired temperatures. Chilling is necessary to preserve perishables and make certain beverages and foods more palatable, especially during long haul and ultra-long haul aircraft journeys. The first method utilizes a standard vapor cycle based air chillers that utilize conventional refrigerant gas compression and expansion technology to generate a secondary re-circulated chilled air loop. The chilled air is generally supplied and returned via thermally insulated air ducting to and from a suitable storage structure, such as a galley. The air chiller may be located on or in the galley or mounted in part of the aircraft airframe.
The second method utilizes the same conventional refrigerant gas compression and expansion technology, but the cooling medium is a chilled liquid rather than a gas. This chilled liquid is pumped in a closed loop to and from a suitable storage structure such as a galley. The chilled liquid in some cases are configured as a large centralized system for the whole aircraft. In other cases, the chilled liquid can be circulated at each separate aircraft door galley complex to form a local area chilling loop, or be based on each individual galley as a standalone system. At the galley, the liquid is passed via a control valve and electronic control system to a heat exchanger, where an electric axial (or other) fan blows or sucks air through its matrix around enclosed areas of the storage structure that requires chilling, for example: a galley cart bay or compartment. The heat exchanger fan and its control system (though not necessarily all) are grouped together to form a chilled air recirculation unit that may be fitted in the galley or remotely spaced from it.
One drawback of these various chiller systems is that they take up a large percentage of available space in the galley, which is at a premium in an aircraft for obvious reasons. Further, the chillers tend to be very heavy, which is also a drawback to their use on aircraft. There are also issues with condensation collection and removal, and the need for improvements in heat transfer efficiency. Accordingly, it would be beneficial to have a chiller system that takes up less space and reflects a reduction in weight over conventional chiller systems currently in use, while providing for condensation collection and improved heat transfer efficiency.